With the recent trend toward temperature increases in automotive engine compartments, engine oil hoses and other rubber parts are required to have a higher resistance to deterioration by oils and heat. In order to meet this demand, an AR has been proposed in JP-A-63-312338, JP-A-63-312339, and others. (The term "JP-A" as used herein means an "unexamined published Japanese patent application".) This AR comprises an acrylic copolymer composition formed from ethylene monomer units and acrylic acid ester monomer units as major components.
The above-described AR, however, is unsuited for practical use without secondary vulcanization. The present inventors have found that this AR does not develop well-balanced initial properties and resistance to permanent compression set, oil and heat if it is vulcanized by primary vulcanization only. Because of the necessity of secondary vulcanization, production of rubber hoses using this material is inefficient.
Development of an AR composition which eliminates the necessity of secondary vulcanization is desirable from the standpoint of improving production efficiency.